It is well known that a container or can with a retained metal cover disk which can be cut away from one of the end walls of the container body along a weakened cutting line provided at a peripheral edge of the disk by raising up and pulling a ring like knob attached to a portion of the retained cover disk. In the container with the retained cover disk for sealing up contents such as, for example tennis balls, therein, the retained metal cover is covered by a removable outer cover made of a flexible material.
In order to remove the retained metal cover disk from the container body, it is necessary to remove the outer flexible cover, raise up the ring like knob from the surface of the retained metal cover disk, and then pull up the knob for cutting off the weakened line on the retained metal cover. There is, however, danger that a hand or finger of the user is often injured with a sharp edge of the metal cover while it is removing from the container body.